Earth & Environment

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SMALL BUT DEADLY The potent toxin epibatidine was first discovered in 1974, when it was isolated from the skin of the phantasmal poison frog, Epipedobates anthonyi (one shown).

R. Tarvin/University of Texas at Austin

ROCK OF AGES Plate tectonics may have started as early as 3.5 billion years ago on Earth. That recycling of Earth’s surface leads to the separation of light-colored continental crust (exposed here at Yosemite National Park’s Half Dome) from darker, denser oceanic crust.

IRMA INCOMING Hurricane Irma passed by Cuba on September 8, 2017, as a Category 4 storm (seen in this geocolor image captured by NOAA’s GOES-16 satellite) before making landfall in the Florida Keys on September 10, 2017.